I have to get a large amount of data from a server to a mobile application.
Currently i am passing the data in XML format which, seems to work.
I want to know if there is another better way to do this.
Also further i may need to show the data using page views.
Note: Using Flex builder 4.6 for development of app.
JSON is always a better choice when there is a data transfer between server-device. It is light-weight and easy to parse.
I personally use blazeds as server with amf-channel for the datas tr/rx...
For large datasets, you'd better use AMF, which is a binary format that will be decoded natively by the flash player.
Depending what technololgy you use server-side, you'll need some bridge that will encode your data in AMF. (BlazeDS/GraniteDS for Java, AMFPHP for PHP, ...)
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We are developing a customized caching solution that will use a SQL Server database to store cached objects. The hosting environment of the application does not provide an "in-memory" cache such as memcached or app fabric so we must use a SQL Server database.
While most of the cached objects will be simple types (int, string, dates, etc) we will need to also store more complex types such as DataSets, DataTables, generic collections and custom classes.
I have very little experience with the .NET's native serialization and deserialization but I figure we will have to serialize the objects into some form (binary, xml, JSON, etc) to store it in the database and then deserialize it when we pull it out of the database. I would like to have some expert opinions on what the the "some form" should be.
We are using JSON.NET to serialize data into JSON for various AJAX requests. My initial thought was to serialize the cached data into JSON to store it in the database. However, I wanted to get a few opinions as to what would be best for performance and data integrity.
All three of the serialization options you mentioned (binary, json or XML) are valid choices for a serialization format. There are many other serialization formats but the three you mentioned are the most common. As to choosing between the three, here are some of the considerations:
If you store your data in a binary format in the database, it is not human readable if if you ever want to look at it via using Sql Server Management Studio or via a text editor. You would have to write some sort of deserialization tool if you wanted to manually peruse the data.
Binary format will likely result in serialize objects have the smallest size, followed by json, with XML being the largest. As far as the actual size differences, that will vary with your data structures.
As far as performance, binary serialization may be faster than json or XML. However, you would have to benchmark this with your data to see what the differences are.
I think there are excellent .net libraries and BCL support for all three of the format types, so any choice should be doable.
So your choice would depend upon which factors are most important to you: CPU utilization, disk storage space, human readability, and/or personal preference.
We have used json extensively for serialization of our objects for storage in a database , using JSON.Net and we like it a lot. It is handy sometimes to manually view the data via SSMS, and json is significantly more compact for our data than XML.
I won't repeat Joe's answer as he is dead on. I want to add that Binary Serialization does increase the complexity if you upgrade the classes. It is manageable but it takes a little work, and requires you to dig into the binary serializer. Where as with a text based approach you could migrate the data using other options (XML you could run XSLT's on it for example)
The cache must be small and fast, and I like to be more specific about what to use.
I suggest the protobuf-net is the same that SO use, I use it, and the speed together with the size is really good. At least on my tests is the smaller and faster.
We use it for the same reason (for cache), after we have try other serializations libraries, this was the faster and smaller in result. Now in a cache schema you do not actually need to see with your eyes whats is inside because is not a setup that you may need to change something because you did not fix yet the function for that.
If you like to see whats on the cache object you can make a simple function that prints it.
I'am new to game maker, and now creating a very simple application, which should get some data from web server (in JSON), and display in special way on device. GameMaker looks to be useful to create this kind of cross-platfrom applications, but it is very difficult for me to find a good samples.
I need to make post request with two name-value pairs ("data", and "info"), and parse result from JSON.
Maybe, someone have a sample, how to do it?
Thanks.
If use GM Studio, use http_post_string, for other versions you have to use extensions.
I have a flex application and need to show the real time data into the chatrs and datagrids.
Eralier we are used Httpservices to showing the real time data and historical data into charts and datagrids. But now we are going to replace the Httpservices to remote objects.
So which places generally need to change. I have a little bit idea about remote objects.
Thanks,
Ravi
If you need to display real time data (or "near real time") you should use some kind of pushing mechanism - take a look on BlazeDS and read about polling and streaming.
If you just need to replace your webservices with remote objects you will need to replace the code dealing with the xml response (extracting data etc) with the code dealing with the objects returned by the remote calls. It is not mandatory to use strongly typed objects, but it will help.
If you are going to replace your HTTPService with RemoteObject, some questions you need riposte yourself.
What framework are you going to implement, if any then check their RemoteObject Invoker Tag if any.
Your resultEvent and FaultEvent will vary according to the framework you are going to apply.
If you are going with Flex default RemoteObject
Then you need to replace all your HTTPService with RemoteObject tags.
Your backend code also requires some changes with business logic should get into methods with the result of function or method returning an object.
Finally a suggestion.
Instead of going with Remote Objects, why not go with Webservice. You can re use the components somewhere else too.
Updated links about Cairngorm
http://www.adobe.com/devnet/flex/articles/cairngorm_pt5_03.html
http://www.jeffryhouser.com/index.cfm/2007/2/19/Learning-Cairngorm-Part-3
http://www.asfusion.com/blog/entry/hello-world-cairngorm-example
http://justjoshn.com/entry/contact-manager-part-2-cairngorm-example
Thanks
It is very simple to retrieve data from a database and display it inside a DataGrid. However, what are the current practices to push the changes in the DataGrid back to the database? One can achieve this by inserting a lot of meta information, however, it is very tedious and not reusable.
There are libraries for persisting data across tiers, but as you say it isn't a simple task. LiveCycle DS ships with this capability when used in conjunction with Hibernate on the server. GraniteDS and Tide can perform a similar function, but for the most part you are left rolling your own. If you are using one of the many MVC frameworks available (I use PureMVC) it isn't difficult to create this type of functionality. Kind of tedious, but not difficult.
Which server side technology would you be using? You need to use HttpServer, WebService or RemoteObject's in Flex to push data to this server side app and that would then update the database.
Unless of course we're talking about a Flex/AIR Desktop App where connecting to databases directly is possible.
You can use RemoteObject, if you have a Java class on the server side that takes care of database connection and provides method to update database.
Just Create an ArrayCollection object from modified datagrid and pass it while doing a method call.
I think making changes to the database is the easiest part of this whole thing. The hardest part is making the DataGrid know exactly from which database table each cell comes from. If you're the one writing the query, then you can probably return a lot of meta-data, such as the private key and table name for each cell.
Our Flex app would like to work with requests and responses as object graphs (nothing unusual there) e.g. response becomes the model of some view, and would be a structure with several layers of nesting.
** Now, ideally we would like to use the same client (and server) side objects for different message formats e.g. XML and AMF, and have a pluggable serialization/de-serialization layer (!)
AMF has serialization and matching of client to server using
[RemoteClass(alias="samples.contact.Contact")]
but it seems there is no equivalent for XML.
I am (somewhat optimistically) looking for a neat way of serializing the object graph to XML, to send through a HTTPService from the client.
For responses, the default 'object' and 'E4X' provide some de-serialization. This is handy, but of course we don't have the niceties of unpacking the XML back into specific AS classes like we do with AMF.
Any suggestions?
(did have one idea come through about wrapping/casting object as XML or XMLList - this does not seem to work, however)
Update:
Both these libraries look useful, and I will very likely use them at some point.
For now, I really need the simplicity of re-using the metadata set for the AMF3 serialization which we are using in any case ([RemoteClass],[Transient])
.. so the best option at the moment is AMFX - used Flex Data Services for AMF transfer using XML - classes in mx.messaging.channels.amfx package - only drawback at the moment is any Externalizable class is transformed into a Hex byte stream - and ArrayCollection is Externalizable! (hoping to workaround by serializing the internal Array in a subclass ..)
Hope that's useful to someone ..
Regarding the Xml serialization I can give you a starting point (as biased as it may be, though :D).
I am working on a project that allows for automatic conversion of AS3 objects to and from xml. It basically uses annotations on the model objects you use for communication in order to construct the xml structure or populating an object from xml.
It is called FlexXB and you can check it out at http://code.google.com/p/flexxb/.
I started this project cos I got into the same issues at work (namely I have a server that communicates through xml) and I hoped it be of use to someone else.
Cheers,
Alex
Yet another project: FleXMLer (http://code.google.com/p/flexmler/).
It has both the straightforward attitude of asx3m where you can just call:
new FleXMLer().serialize(obj);
Or you can customize XML element names, skip elements and tweak the way arrays and hash tables are serialized.
Would appreciate your input.
checkout asx3m project at http://code.google.com/p/asx3m
It's an AS3 port of Java XStream serialization library and works pretty well.
I made it because I had to connect to a server platform that used XStream for exchanging data objects and put a lot of work in it.
It can be extended to serialize AS3 objects to any format (JSON for example) and could leverage power of user defined metatags.
Cheers,
Tomislav
There's a library including JSON available from Adobe, too. And since ActionScript is a superset of JavaScript ... and JSON is increasingly supported cross-framework ...